Trench type MOSgated devices such as power MOSFETs and IGBTs are well known, wherein an insulation gate lines the side walls in spaced trenches, covering an invertible channel region along at least portions of the walls of the trench. A conductive polysilicon gate then fills the trenches.
The on resistance and the gate charge of the device is determined, in part, by the carrier mobility in this channel region.
It would be desirable to increase the mobility of the channel region in a trench device or, indeed, in a lateral surface channel of a planar device, to reduce on resistance and improve high speed switching performance.